Long Latency Period After Exposure

Virtually no increases in death rates, either overall or for specific diseases, were seen in the first 15 years after onset of exposure, and comparatively little after that until 25 or 30 years had passed.

If the same were to be true for disease that might be associated with manmade mineral fibers, for example, the first 30 years of observation of cohorts of individuals exposed to such fibers would provide little information with regard to potential neoplastic toxicity; (epidemiologically, such information would constitute empty data). Figures 1 and 2 depict the incidence of deaths of asbestosis and peritoneal mesothelioma following onset of work exposure.

Parenthetically, if we were to truncate epidemiological mortality studies of asbestos-exposed workers at age 65, a practice sometimes recommended for cancer studies in general, it would be difficult to fully appreciate the importance of latency in the evaluation of the incidence of asbestos-associated cancer. Figures 3 and 4 indicate that approximately one-third of the deaths of mesothelioma, for example, occurred after age 65.

To review the data contained in these figures, refer to Page 273 of Dr. Selikoff’s report. To review the references in Dr. Selikoff’s article see Pages 275-276.